Planar, sheet-like structures of the type currently used as partitions in restrooms are homogeneous solid structures formed of thermoplastic material, typically polyethylene. While structures currently used as restroom partitions function effectively, they are expensive to manufacture and do not resist defacing by users of the restrooms, particularly public restrooms. Cigarettes and other tobacco products, when urged against the partition structures in public restrooms leave unsightly marks requiring repainting or other repair. This is a substantial disadvantage with known, currently commercially used structures.
Concerning printed prior art, U.S. Pat. Nos. 3,565,746; 3,630,819, 3,637,459; 3,640,938; 3,753,843; 3,846,524; 3,884,646, 3,859,401; 3,936,565; 3,940,468; 3,940,526; 3,977,931; 4,013,810; 4,035,536; 4,053,545; 4,262,052; 4,301,216; 4,351,870; 4,440,825 and 4,543,289 are known to applicant. Of these patents, '843 is believed to be by far the most relevant.
'843 discloses a molded panel having plastic on two outwardly facing surfaces and a honeycomb-type interior core. The panel is molded and has a flowable, hardenable urethene-based plastic foam as the face material.
Also relevant are assertions set forth in '646 and '810, stating in substance that it is old in the art to use honeycomb as one component in composite structures.
'870 discloses interface junctions between cellular core material and outwardly facing sheets produced by thermal and/or pressured-induced adhesive bonds. However, '870 does not suggest use of metal or other high strength material as the cellular core, only suggesting using a strength-increasing metal layer, at column 3, line 65. '870 suggests that the interior material might be a foam or other hollow cellular material, at column 3, line 29.
The other patents noted are less relevant.